This invention relates generally to surgically implanted shunt systems utilized to drain cerebrospinal fluid from a brain ventricle. More particularly, the present invention relates to stylets utilized to introduce ventricular catheters utilized in cerebrospinal fluid shunt systems.
As is well known in the medical arts, to relieve undesirable accumulation of fluids it is frequently necessary to provide a means for draining a fluid from one part of the human body to another in a controlled manner. This is required, for example, in the treatment of hydrocephalus, an ailment usually afflicting infants or children in which fluids which ought to drain away instead accumulate within the skull and thereby exert extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain ventricles is drained away by a catheter inserted into a ventricle through the skull, and the catheter is connected to a tube which conducts the fluid away from the brain to be reintroduced into the vascular system, as by extending through the patient's jugular vein to the atrium portion of the heart. To control the flow of cerebrospinal fluid and maintain the proper pressure in the brain ventricle, a pump or valve is placed in the conduit between the brain and the heart. The brain ventricles are normally large enough to easily accommodate the end of a catheter several millimeters in diameter. Such ventricular catheters are commonly provided with small holes through their walls for receiving cerebrospinal fluid from the ventricle. To insert the ventricular catheter, a hole is bored through the skull, and a solid stylet is utilized as an introducer to properly position the flexible catheter within the ventricle.
Since cerebrospinal fluid within the brain ventricles is normally maintained under pressure, proper placement of a distal end of the ventricular catheter is indicated when the cerebrospinal fluid flows through the catheter inlet apertures and is presented at a catheter proximal end. A solid stylet, however, tends to occlude the internal fluid flow passageway through the catheter, thereby requiring the stylet to be withdrawn from the catheter in order to determine whether the distal end thereof is properly positioned. If the expected "flashback" of cerebrospinal fluid is not found at the proximal end of the catheter upon removal of the solid stylet, the stylet must be reinserted for further positioning of the ventricular catheter.
Accordingly, there has been a need for a novel stylet assembly useful for inserting a catheter into a brain ventricle and providing a cerebrospinal fluid flashback indicia of proper catheter positioning, without requiring withdrawal of the stylet assembly from the ventricular catheter. Such a stylet assembly should be of simplified construction utilizing materials which are easily sterilizable and compatible for biomedical usage. Further, there exists a need for a stylet assembly for inserting a catheter into a body cavity and providing a flashback indicia of catheter positioning, which permits the surgeon to readily occlude the fluid passageway when proper catheter positioning is indicated, in order to minimize and control the flow of fluid from the body cavity through the catheter. The present invention fulfills these needs and provides other related advantages.